daemon.c

   1 #include "cache.h"
   2 #include "pkt-line.h"
   3 #include "exec_cmd.h"
   4 #include "run-command.h"
   5 #include "strbuf.h"
   6 #include "string-list.h"
   7
   8 #ifndef HOST_NAME_MAX
   9 #define HOST_NAME_MAX 256
  10 #endif
  11
  12 #ifdef NO_INITGROUPS
  13 #define initgroups(x, y) (0) /* nothing */
  14 #endif
  15
  16 static int log_syslog;
  17 static int verbose;
  18 static int reuseaddr;
  19 static int informative_errors;
  20
  21 static const char daemon_usage[] =
  22 "git daemon [--verbose] [--syslog] [--export-all]\n"
  23 "           [--timeout=<n>] [--init-timeout=<n>] [--max-connections=<n>]\n"
  24 "           [--strict-paths] [--base-path=<path>] [--base-path-relaxed]\n"
  25 "           [--user-path | --user-path=<path>]\n"
  26 "           [--interpolated-path=<path>]\n"
  27 "           [--reuseaddr] [--pid-file=<file>]\n"
  28 "           [--(enable|disable|allow-override|forbid-override)=<service>]\n"
  29 "           [--access-hook=<path>]\n"
  30 "           [--inetd | [--listen=<host_or_ipaddr>] [--port=<n>]\n"
  31 "                      [--detach] [--user=<user> [--group=<group>]]\n"
  32 "           [<directory>...]";
  33
  34 /* List of acceptable pathname prefixes */
  35 static char **ok_paths;
  36 static int strict_paths;
  37
  38 /* If this is set, git-daemon-export-ok is not required */
  39 static int export_all_trees;
  40
  41 /* Take all paths relative to this one if non-NULL */
  42 static const char *base_path;
  43 static const char *interpolated_path;
  44 static int base_path_relaxed;
  45
  46 /* Flag indicating client sent extra args. */
  47 static int saw_extended_args;
  48
  49 /* If defined, ~user notation is allowed and the string is inserted
  50  * after ~user/.  E.g. a request to git://host/~alice/frotz would
  51  * go to /home/alice/pub_git/frotz with --user-path=pub_git.
  52  */
  53 static const char *user_path;
  54
  55 /* Timeout, and initial timeout */
  56 static unsigned int timeout;
  57 static unsigned int init_timeout;
  58
  59 static struct strbuf hostname = STRBUF_INIT;
  60 static struct strbuf canon_hostname = STRBUF_INIT;
  61 static struct strbuf ip_address = STRBUF_INIT;
  62 static struct strbuf tcp_port = STRBUF_INIT;
  63
  64 static int hostname_lookup_done;
  65
  66 static void lookup_hostname(void);
  67
  68 static const char *get_canon_hostname(void)
  69 {
  70         lookup_hostname();
  71         return canon_hostname.buf;
  72 }
  73
  74 static const char *get_ip_address(void)
  75 {
  76         lookup_hostname();
  77         return ip_address.buf;
  78 }
  79
  80 static void logreport(int priority, const char *err, va_list params)
  81 {
  82         if (log_syslog) {
  83                 char buf[1024];
  84                 vsnprintf(buf, sizeof(buf), err, params);
  85                 syslog(priority, "%s", buf);
  86         } else {
  87                 /*
  88                  * Since stderr is set to buffered mode, the
  89                  * logging of different processes will not overlap
  90                  * unless they overflow the (rather big) buffers.
  91                  */
  92                 fprintf(stderr, "[%"PRIuMAX"] ", (uintmax_t)getpid());
  93                 vfprintf(stderr, err, params);
  94                 fputc('\n', stderr);
  95                 fflush(stderr);
  96         }
  97 }
  98
  99 __attribute__((format (printf, 1, 2)))
 100 static void logerror(const char *err, ...)
 101 {
 102         va_list params;
 103         va_start(params, err);
 104         logreport(LOG_ERR, err, params);
 105         va_end(params);
 106 }
 107
 108 __attribute__((format (printf, 1, 2)))
 109 static void loginfo(const char *err, ...)
 110 {
 111         va_list params;
 112         if (!verbose)
 113                 return;
 114         va_start(params, err);
 115         logreport(LOG_INFO, err, params);
 116         va_end(params);
 117 }
 118
 119 static void NORETURN daemon_die(const char *err, va_list params)
 120 {
 121         logreport(LOG_ERR, err, params);
 122         exit(1);
 123 }
 124
 125 struct expand_path_context {
 126         const char *directory;
 127 };
 128
 129 static size_t expand_path(struct strbuf *sb, const char *placeholder, void *ctx)
 130 {
 131         struct expand_path_context *context = ctx;
 132
 133         switch (placeholder[0]) {
 134         case 'H':
 135                 strbuf_addbuf(sb, &hostname);
 136                 return 1;
 137         case 'C':
 138                 if (placeholder[1] == 'H') {
 139                         strbuf_addstr(sb, get_canon_hostname());
 140                         return 2;
 141                 }
 142                 break;
 143         case 'I':
 144                 if (placeholder[1] == 'P') {
 145                         strbuf_addstr(sb, get_ip_address());
 146                         return 2;
 147                 }
 148                 break;
 149         case 'P':
 150                 strbuf_addbuf(sb, &tcp_port);
 151                 return 1;
 152         case 'D':
 153                 strbuf_addstr(sb, context->directory);
 154                 return 1;
 155         }
 156         return 0;
 157 }
 158
 159 static const char *path_ok(const char *directory)
 160 {
 161         static char rpath[PATH_MAX];
 162         static char interp_path[PATH_MAX];
 163         const char *path;
 164         const char *dir;
 165
 166         dir = directory;
 167
 168         if (daemon_avoid_alias(dir)) {
 169                 logerror("'%s': aliased", dir);
 170                 return NULL;
 171         }
 172
 173         if (*dir == '~') {
 174                 if (!user_path) {
 175                         logerror("'%s': User-path not allowed", dir);
 176                         return NULL;
 177                 }
 178                 if (*user_path) {
 179                         /* Got either "~alice" or "~alice/foo";
 180                          * rewrite them to "~alice/%s" or
 181                          * "~alice/%s/foo".
 182                          */
 183                         int namlen, restlen = strlen(dir);
 184                         const char *slash = strchr(dir, '/');
 185                         if (!slash)
 186                                 slash = dir + restlen;
 187                         namlen = slash - dir;
 188                         restlen -= namlen;
 189                         loginfo("userpath <%s>, request <%s>, namlen %d, restlen %d, slash <%s>", user_path, dir, namlen, restlen, slash);
 190                         snprintf(rpath, PATH_MAX, "%.*s/%s%.*s",
 191                                  namlen, dir, user_path, restlen, slash);
 192                         dir = rpath;
 193                 }
 194         }
 195         else if (interpolated_path && saw_extended_args) {
 196                 struct strbuf expanded_path = STRBUF_INIT;
 197                 struct expand_path_context context;
 198
 199                 context.directory = directory;
 200
 201                 if (*dir != '/') {
 202                         /* Allow only absolute */
 203                         logerror("'%s': Non-absolute path denied (interpolated-path active)", dir);
 204                         return NULL;
 205                 }
 206
 207                 strbuf_expand(&expanded_path, interpolated_path,
 208                               expand_path, &context);
 209                 strlcpy(interp_path, expanded_path.buf, PATH_MAX);
 210                 strbuf_release(&expanded_path);
 211                 loginfo("Interpolated dir '%s'", interp_path);
 212
 213                 dir = interp_path;
 214         }
 215         else if (base_path) {
 216                 if (*dir != '/') {
 217                         /* Allow only absolute */
 218                         logerror("'%s': Non-absolute path denied (base-path active)", dir);
 219                         return NULL;
 220                 }
 221                 snprintf(rpath, PATH_MAX, "%s%s", base_path, dir);
 222                 dir = rpath;
 223         }
 224
 225         path = enter_repo(dir, strict_paths);
 226         if (!path && base_path && base_path_relaxed) {
 227                 /*
 228                  * if we fail and base_path_relaxed is enabled, try without
 229                  * prefixing the base path
 230                  */
 231                 dir = directory;
 232                 path = enter_repo(dir, strict_paths);
 233         }
 234
 235         if (!path) {
 236                 logerror("'%s' does not appear to be a git repository", dir);
 237                 return NULL;
 238         }
 239
 240         if ( ok_paths && *ok_paths ) {
 241                 char **pp;
 242                 int pathlen = strlen(path);
 243
 244                 /* The validation is done on the paths after enter_repo
 245                  * appends optional {.git,.git/.git} and friends, but
 246                  * it does not use getcwd().  So if your /pub is
 247                  * a symlink to /mnt/pub, you can whitelist /pub and
 248                  * do not have to say /mnt/pub.
 249                  * Do not say /pub/.
 250                  */
 251                 for ( pp = ok_paths ; *pp ; pp++ ) {
 252                         int len = strlen(*pp);
 253                         if (len <= pathlen &&
 254                             !memcmp(*pp, path, len) &&
 255                             (path[len] == '\0' ||
 256                              (!strict_paths && path[len] == '/')))
 257                                 return path;
 258                 }
 259         }
 260         else {
 261                 /* be backwards compatible */
 262                 if (!strict_paths)
 263                         return path;
 264         }
 265
 266         logerror("'%s': not in whitelist", path);
 267         return NULL;            /* Fallthrough. Deny by default */
 268 }
 269
 270 typedef int (*daemon_service_fn)(void);
 271 struct daemon_service {
 272         const char *name;
 273         const char *config_name;
 274         daemon_service_fn fn;
 275         int enabled;
 276         int overridable;
 277 };
 278
 279 static int daemon_error(const char *dir, const char *msg)
 280 {
 281         if (!informative_errors)
 282                 msg = "access denied or repository not exported";
 283         packet_write(1, "ERR %s: %s", msg, dir);
 284         return -1;
 285 }
 286
 287 static const char *access_hook;
 288
 289 static int run_access_hook(struct daemon_service *service, const char *dir, const char *path)
 290 {
 291         struct child_process child = CHILD_PROCESS_INIT;
 292         struct strbuf buf = STRBUF_INIT;
 293         const char *argv[8];
 294         const char **arg = argv;
 295         char *eol;
 296         int seen_errors = 0;
 297
 298         *arg++ = access_hook;
 299         *arg++ = service->name;
 300         *arg++ = path;
 301         *arg++ = hostname.buf;
 302         *arg++ = get_canon_hostname();
 303         *arg++ = get_ip_address();
 304         *arg++ = tcp_port.buf;
 305         *arg = NULL;
 306
 307         child.use_shell = 1;
 308         child.argv = argv;
 309         child.no_stdin = 1;
 310         child.no_stderr = 1;
 311         child.out = -1;
 312         if (start_command(&child)) {
 313                 logerror("daemon access hook '%s' failed to start",
 314                          access_hook);
 315                 goto error_return;
 316         }
 317         if (strbuf_read(&buf, child.out, 0) < 0) {
 318                 logerror("failed to read from pipe to daemon access hook '%s'",
 319                          access_hook);
 320                 strbuf_reset(&buf);
 321                 seen_errors = 1;
 322         }
 323         if (close(child.out) < 0) {
 324                 logerror("failed to close pipe to daemon access hook '%s'",
 325                          access_hook);
 326                 seen_errors = 1;
 327         }
 328         if (finish_command(&child))
 329                 seen_errors = 1;
 330
 331         if (!seen_errors) {
 332                 strbuf_release(&buf);
 333                 return 0;
 334         }
 335
 336 error_return:
 337         strbuf_ltrim(&buf);
 338         if (!buf.len)
 339                 strbuf_addstr(&buf, "service rejected");
 340         eol = strchr(buf.buf, '\n');
 341         if (eol)
 342                 *eol = '\0';
 343         errno = EACCES;
 344         daemon_error(dir, buf.buf);
 345         strbuf_release(&buf);
 346         return -1;
 347 }
 348
 349 static int run_service(const char *dir, struct daemon_service *service)
 350 {
 351         const char *path;
 352         int enabled = service->enabled;
 353         struct strbuf var = STRBUF_INIT;
 354
 355         loginfo("Request %s for '%s'", service->name, dir);
 356
 357         if (!enabled && !service->overridable) {
 358                 logerror("'%s': service not enabled.", service->name);
 359                 errno = EACCES;
 360                 return daemon_error(dir, "service not enabled");
 361         }
 362
 363         if (!(path = path_ok(dir)))
 364                 return daemon_error(dir, "no such repository");
 365
 366         /*
 367          * Security on the cheap.
 368          *
 369          * We want a readable HEAD, usable "objects" directory, and
 370          * a "git-daemon-export-ok" flag that says that the other side
 371          * is ok with us doing this.
 372          *
 373          * path_ok() uses enter_repo() and does whitelist checking.
 374          * We only need to make sure the repository is exported.
 375          */
 376
 377         if (!export_all_trees && access("git-daemon-export-ok", F_OK)) {
 378                 logerror("'%s': repository not exported.", path);
 379                 errno = EACCES;
 380                 return daemon_error(dir, "repository not exported");
 381         }
 382
 383         if (service->overridable) {
 384                 strbuf_addf(&var, "daemon.%s", service->config_name);
 385                 git_config_get_bool(var.buf, &enabled);
 386                 strbuf_release(&var);
 387         }
 388         if (!enabled) {
 389                 logerror("'%s': service not enabled for '%s'",
 390                          service->name, path);
 391                 errno = EACCES;
 392                 return daemon_error(dir, "service not enabled");
 393         }
 394
 395         /*
 396          * Optionally, a hook can choose to deny access to the
 397          * repository depending on the phase of the moon.
 398          */
 399         if (access_hook && run_access_hook(service, dir, path))
 400                 return -1;
 401
 402         /*
 403          * We'll ignore SIGTERM from now on, we have a
 404          * good client.
 405          */
 406         signal(SIGTERM, SIG_IGN);
 407
 408         return service->fn();
 409 }
 410
 411 static void copy_to_log(int fd)
 412 {
 413         struct strbuf line = STRBUF_INIT;
 414         FILE *fp;
 415
 416         fp = fdopen(fd, "r");
 417         if (fp == NULL) {
 418                 logerror("fdopen of error channel failed");
 419                 close(fd);
 420                 return;
 421         }
 422
 423         while (strbuf_getline(&line, fp, '\n') != EOF) {
 424                 logerror("%s", line.buf);
 425                 strbuf_setlen(&line, 0);
 426         }
 427
 428         strbuf_release(&line);
 429         fclose(fp);
 430 }
 431
 432 static int run_service_command(const char **argv)
 433 {
 434         struct child_process cld = CHILD_PROCESS_INIT;
 435
 436         cld.argv = argv;
 437         cld.git_cmd = 1;
 438         cld.err = -1;
 439         if (start_command(&cld))
 440                 return -1;
 441
 442         close(0);
 443         close(1);
 444
 445         copy_to_log(cld.err);
 446
 447         return finish_command(&cld);
 448 }
 449
 450 static int upload_pack(void)
 451 {
 452         /* Timeout as string */
 453         char timeout_buf[64];
 454         const char *argv[] = { "upload-pack", "--strict", NULL, ".", NULL };
 455
 456         argv[2] = timeout_buf;
 457
 458         snprintf(timeout_buf, sizeof timeout_buf, "--timeout=%u", timeout);
 459         return run_service_command(argv);
 460 }
 461
 462 static int upload_archive(void)
 463 {
 464         static const char *argv[] = { "upload-archive", ".", NULL };
 465         return run_service_command(argv);
 466 }
 467
 468 static int receive_pack(void)
 469 {
 470         static const char *argv[] = { "receive-pack", ".", NULL };
 471         return run_service_command(argv);
 472 }
 473
 474 static struct daemon_service daemon_service[] = {
 475         { "upload-archive", "uploadarch", upload_archive, 0, 1 },
 476         { "upload-pack", "uploadpack", upload_pack, 1, 1 },
 477         { "receive-pack", "receivepack", receive_pack, 0, 1 },
 478 };
 479
 480 static void enable_service(const char *name, int ena)
 481 {
 482         int i;
 483         for (i = 0; i < ARRAY_SIZE(daemon_service); i++) {
 484                 if (!strcmp(daemon_service[i].name, name)) {
 485                         daemon_service[i].enabled = ena;
 486                         return;
 487                 }
 488         }
 489         die("No such service %s", name);
 490 }
 491
 492 static void make_service_overridable(const char *name, int ena)
 493 {
 494         int i;
 495         for (i = 0; i < ARRAY_SIZE(daemon_service); i++) {
 496                 if (!strcmp(daemon_service[i].name, name)) {
 497                         daemon_service[i].overridable = ena;
 498                         return;
 499                 }
 500         }
 501         die("No such service %s", name);
 502 }
 503
 504 static void parse_host_and_port(char *hostport, char **host,
 505         char **port)
 506 {
 507         if (*hostport == '[') {
 508                 char *end;
 509
 510                 end = strchr(hostport, ']');
 511                 if (!end)
 512                         die("Invalid request ('[' without ']')");
 513                 *end = '\0';
 514                 *host = hostport + 1;
 515                 if (!end[1])
 516                         *port = NULL;
 517                 else if (end[1] == ':')
 518                         *port = end + 2;
 519                 else
 520                         die("Garbage after end of host part");
 521         } else {
 522                 *host = hostport;
 523                 *port = strrchr(hostport, ':');
 524                 if (*port) {
 525                         **port = '\0';
 526                         ++*port;
 527                 }
 528         }
 529 }
 530
 531 /*
 532  * Sanitize a string from the client so that it's OK to be inserted into a
 533  * filesystem path. Specifically, we disallow slashes, runs of "..", and
 534  * trailing and leading dots, which means that the client cannot escape
 535  * our base path via ".." traversal.
 536  */
 537 static void sanitize_client(struct strbuf *out, const char *in)
 538 {
 539         for (; *in; in++) {
 540                 if (*in == '/')
 541                         continue;
 542                 if (*in == '.' && (!out->len || out->buf[out->len - 1] == '.'))
 543                         continue;
 544                 strbuf_addch(out, *in);
 545         }
 546
 547         while (out->len && out->buf[out->len - 1] == '.')
 548                 strbuf_setlen(out, out->len - 1);
 549 }
 550
 551 /*
 552  * Like sanitize_client, but we also perform any canonicalization
 553  * to make life easier on the admin.
 554  */
 555 static void canonicalize_client(struct strbuf *out, const char *in)
 556 {
 557         sanitize_client(out, in);
 558         strbuf_tolower(out);
 559 }
 560
 561 /*
 562  * Read the host as supplied by the client connection.
 563  */
 564 static void parse_host_arg(char *extra_args, int buflen)
 565 {
 566         char *val;
 567         int vallen;
 568         char *end = extra_args + buflen;
 569
 570         if (extra_args < end && *extra_args) {
 571                 saw_extended_args = 1;
 572                 if (strncasecmp("host=", extra_args, 5) == 0) {
 573                         val = extra_args + 5;
 574                         vallen = strlen(val) + 1;
 575                         if (*val) {
 576                                 /* Split <host>:<port> at colon. */
 577                                 char *host;
 578                                 char *port;
 579                                 parse_host_and_port(val, &host, &port);
 580                                 if (port) {
 581                                         strbuf_reset(&tcp_port);
 582                                         sanitize_client(&tcp_port, port);
 583                                 }
 584                                 strbuf_reset(&hostname);
 585                                 canonicalize_client(&hostname, host);
 586                                 hostname_lookup_done = 0;
 587                         }
 588
 589                         /* On to the next one */
 590                         extra_args = val + vallen;
 591                 }
 592                 if (extra_args < end && *extra_args)
 593                         die("Invalid request");
 594         }
 595 }
 596
 597 /*
 598  * Locate canonical hostname and its IP address.
 599  */
 600 static void lookup_hostname(void)
 601 {
 602         if (!hostname_lookup_done && hostname.len) {
 603 #ifndef NO_IPV6
 604                 struct addrinfo hints;
 605                 struct addrinfo *ai;
 606                 int gai;
 607                 static char addrbuf[HOST_NAME_MAX + 1];
 608
 609                 memset(&hints, 0, sizeof(hints));
 610                 hints.ai_flags = AI_CANONNAME;
 611
 612                 gai = getaddrinfo(hostname.buf, NULL, &hints, &ai);
 613                 if (!gai) {
 614                         struct sockaddr_in *sin_addr = (void *)ai->ai_addr;
 615
 616                         inet_ntop(AF_INET, &sin_addr->sin_addr,
 617                                   addrbuf, sizeof(addrbuf));
 618                         strbuf_reset(&ip_address);
 619                         strbuf_addstr(&ip_address, addrbuf);
 620
 621                         strbuf_reset(&canon_hostname);
 622                         if (ai->ai_canonname)
 623                                 sanitize_client(&canon_hostname,
 624                                                 ai->ai_canonname);
 625                         else
 626                                 strbuf_addbuf(&canon_hostname, &ip_address);
 627
 628                         freeaddrinfo(ai);
 629                 }
 630 #else
 631                 struct hostent *hent;
 632                 struct sockaddr_in sa;
 633                 char **ap;
 634                 static char addrbuf[HOST_NAME_MAX + 1];
 635
 636                 hent = gethostbyname(hostname.buf);
 637                 if (hent) {
 638                         ap = hent->h_addr_list;
 639                         memset(&sa, 0, sizeof sa);
 640                         sa.sin_family = hent->h_addrtype;
 641                         sa.sin_port = htons(0);
 642                         memcpy(&sa.sin_addr, *ap, hent->h_length);
 643
 644                         inet_ntop(hent->h_addrtype, &sa.sin_addr,
 645                                   addrbuf, sizeof(addrbuf));
 646
 647                         strbuf_reset(&canon_hostname);
 648                         sanitize_client(&canon_hostname, hent->h_name);
 649                         strbuf_reset(&ip_address);
 650                         strbuf_addstr(&ip_address, addrbuf);
 651                 }
 652 #endif
 653                 hostname_lookup_done = 1;
 654         }
 655 }
 656
 657
 658 static int execute(void)
 659 {
 660         char *line = packet_buffer;
 661         int pktlen, len, i;
 662         char *addr = getenv("REMOTE_ADDR"), *port = getenv("REMOTE_PORT");
 663
 664         if (addr)
 665                 loginfo("Connection from %s:%s", addr, port);
 666
 667         alarm(init_timeout ? init_timeout : timeout);
 668         pktlen = packet_read(0, NULL, NULL, packet_buffer, sizeof(packet_buffer), 0);
 669         alarm(0);
 670
 671         len = strlen(line);
 672         if (pktlen != len)
 673                 loginfo("Extended attributes (%d bytes) exist <%.*s>",
 674                         (int) pktlen - len,
 675                         (int) pktlen - len, line + len + 1);
 676         if (len && line[len-1] == '\n') {
 677                 line[--len] = 0;
 678                 pktlen--;
 679         }
 680
 681         strbuf_release(&hostname);
 682         strbuf_release(&canon_hostname);
 683         strbuf_release(&ip_address);
 684         strbuf_release(&tcp_port);
 685
 686         if (len != pktlen)
 687                 parse_host_arg(line + len + 1, pktlen - len - 1);
 688
 689         for (i = 0; i < ARRAY_SIZE(daemon_service); i++) {
 690                 struct daemon_service *s = &(daemon_service[i]);
 691                 const char *arg;
 692
 693                 if (skip_prefix(line, "git-", &arg) &&
 694                     skip_prefix(arg, s->name, &arg) &&
 695                     *arg++ == ' ') {
 696                         /*
 697                          * Note: The directory here is probably context sensitive,
 698                          * and might depend on the actual service being performed.
 699                          */
 700                         return run_service(arg, s);
 701                 }
 702         }
 703
 704         logerror("Protocol error: '%s'", line);
 705         return -1;
 706 }
 707
 708 static int addrcmp(const struct sockaddr_storage *s1,
 709     const struct sockaddr_storage *s2)
 710 {
 711         const struct sockaddr *sa1 = (const struct sockaddr*) s1;
 712         const struct sockaddr *sa2 = (const struct sockaddr*) s2;
 713
 714         if (sa1->sa_family != sa2->sa_family)
 715                 return sa1->sa_family - sa2->sa_family;
 716         if (sa1->sa_family == AF_INET)
 717                 return memcmp(&((struct sockaddr_in *)s1)->sin_addr,
 718                     &((struct sockaddr_in *)s2)->sin_addr,
 719                     sizeof(struct in_addr));
 720 #ifndef NO_IPV6
 721         if (sa1->sa_family == AF_INET6)
 722                 return memcmp(&((struct sockaddr_in6 *)s1)->sin6_addr,
 723                     &((struct sockaddr_in6 *)s2)->sin6_addr,
 724                     sizeof(struct in6_addr));
 725 #endif
 726         return 0;
 727 }
 728
 729 static int max_connections = 32;
 730
 731 static unsigned int live_children;
 732
 733 static struct child {
 734         struct child *next;
 735         struct child_process cld;
 736         struct sockaddr_storage address;
 737 } *firstborn;
 738
 739 static void add_child(struct child_process *cld, struct sockaddr *addr, socklen_t addrlen)
 740 {
 741         struct child *newborn, **cradle;
 742
 743         newborn = xcalloc(1, sizeof(*newborn));
 744         live_children++;
 745         memcpy(&newborn->cld, cld, sizeof(*cld));
 746         memcpy(&newborn->address, addr, addrlen);
 747         for (cradle = &firstborn; *cradle; cradle = &(*cradle)->next)
 748                 if (!addrcmp(&(*cradle)->address, &newborn->address))
 749                         break;
 750         newborn->next = *cradle;
 751         *cradle = newborn;
 752 }
 753
 754 /*
 755  * This gets called if the number of connections grows
 756  * past "max_connections".
 757  *
 758  * We kill the newest connection from a duplicate IP.
 759  */
 760 static void kill_some_child(void)
 761 {
 762         const struct child *blanket, *next;
 763
 764         if (!(blanket = firstborn))
 765                 return;
 766
 767         for (; (next = blanket->next); blanket = next)
 768                 if (!addrcmp(&blanket->address, &next->address)) {
 769                         kill(blanket->cld.pid, SIGTERM);
 770                         break;
 771                 }
 772 }
 773
 774 static void check_dead_children(void)
 775 {
 776         int status;
 777         pid_t pid;
 778
 779         struct child **cradle, *blanket;
 780         for (cradle = &firstborn; (blanket = *cradle);)
 781                 if ((pid = waitpid(blanket->cld.pid, &status, WNOHANG)) > 1) {
 782                         const char *dead = "";
 783                         if (status)
 784                                 dead = " (with error)";
 785                         loginfo("[%"PRIuMAX"] Disconnected%s", (uintmax_t)pid, dead);
 786
 787                         /* remove the child */
 788                         *cradle = blanket->next;
 789                         live_children--;
 790                         free(blanket);
 791                 } else
 792                         cradle = &blanket->next;
 793 }
 794
 795 static char **cld_argv;
 796 static void handle(int incoming, struct sockaddr *addr, socklen_t addrlen)
 797 {
 798         struct child_process cld = CHILD_PROCESS_INIT;
 799         char addrbuf[300] = "REMOTE_ADDR=", portbuf[300];
 800         char *env[] = { addrbuf, portbuf, NULL };
 801
 802         if (max_connections && live_children >= max_connections) {
 803                 kill_some_child();
 804                 sleep(1);  /* give it some time to die */
 805                 check_dead_children();
 806                 if (live_children >= max_connections) {
 807                         close(incoming);
 808                         logerror("Too many children, dropping connection");
 809                         return;
 810                 }
 811         }
 812
 813         if (addr->sa_family == AF_INET) {
 814                 struct sockaddr_in *sin_addr = (void *) addr;
 815                 inet_ntop(addr->sa_family, &sin_addr->sin_addr, addrbuf + 12,
 816                     sizeof(addrbuf) - 12);
 817                 snprintf(portbuf, sizeof(portbuf), "REMOTE_PORT=%d",
 818                     ntohs(sin_addr->sin_port));
 819 #ifndef NO_IPV6
 820         } else if (addr->sa_family == AF_INET6) {
 821                 struct sockaddr_in6 *sin6_addr = (void *) addr;
 822
 823                 char *buf = addrbuf + 12;
 824                 *buf++ = '['; *buf = '\0'; /* stpcpy() is cool */
 825                 inet_ntop(AF_INET6, &sin6_addr->sin6_addr, buf,
 826                     sizeof(addrbuf) - 13);
 827                 strcat(buf, "]");
 828
 829                 snprintf(portbuf, sizeof(portbuf), "REMOTE_PORT=%d",
 830                     ntohs(sin6_addr->sin6_port));
 831 #endif
 832         }
 833
 834         cld.env = (const char **)env;
 835         cld.argv = (const char **)cld_argv;
 836         cld.in = incoming;
 837         cld.out = dup(incoming);
 838
 839         if (start_command(&cld))
 840                 logerror("unable to fork");
 841         else
 842                 add_child(&cld, addr, addrlen);
 843 }
 844
 845 static void child_handler(int signo)
 846 {
 847         /*
 848          * Otherwise empty handler because systemcalls will get interrupted
 849          * upon signal receipt
 850          * SysV needs the handler to be rearmed
 851          */
 852         signal(SIGCHLD, child_handler);
 853 }
 854
 855 static int set_reuse_addr(int sockfd)
 856 {
 857         int on = 1;
 858
 859         if (!reuseaddr)
 860                 return 0;
 861         return setsockopt(sockfd, SOL_SOCKET, SO_REUSEADDR,
 862                           &on, sizeof(on));
 863 }
 864
 865 struct socketlist {
 866         int *list;
 867         size_t nr;
 868         size_t alloc;
 869 };
 870
 871 static const char *ip2str(int family, struct sockaddr *sin, socklen_t len)
 872 {
 873 #ifdef NO_IPV6
 874         static char ip[INET_ADDRSTRLEN];
 875 #else
 876         static char ip[INET6_ADDRSTRLEN];
 877 #endif
 878
 879         switch (family) {
 880 #ifndef NO_IPV6
 881         case AF_INET6:
 882                 inet_ntop(family, &((struct sockaddr_in6*)sin)->sin6_addr, ip, len);
 883                 break;
 884 #endif
 885         case AF_INET:
 886                 inet_ntop(family, &((struct sockaddr_in*)sin)->sin_addr, ip, len);
 887                 break;
 888         default:
 889                 strcpy(ip, "<unknown>");
 890         }
 891         return ip;
 892 }
 893
 894 #ifndef NO_IPV6
 895
 896 static int setup_named_sock(char *listen_addr, int listen_port, struct socketlist *socklist)
 897 {
 898         int socknum = 0;
 899         char pbuf[NI_MAXSERV];
 900         struct addrinfo hints, *ai0, *ai;
 901         int gai;
 902         long flags;
 903
 904         sprintf(pbuf, "%d", listen_port);
 905         memset(&hints, 0, sizeof(hints));
 906         hints.ai_family = AF_UNSPEC;
 907         hints.ai_socktype = SOCK_STREAM;
 908         hints.ai_protocol = IPPROTO_TCP;
 909         hints.ai_flags = AI_PASSIVE;
 910
 911         gai = getaddrinfo(listen_addr, pbuf, &hints, &ai0);
 912         if (gai) {
 913                 logerror("getaddrinfo() for %s failed: %s", listen_addr, gai_strerror(gai));
 914                 return 0;
 915         }
 916
 917         for (ai = ai0; ai; ai = ai->ai_next) {
 918                 int sockfd;
 919
 920                 sockfd = socket(ai->ai_family, ai->ai_socktype, ai->ai_protocol);
 921                 if (sockfd < 0)
 922                         continue;
 923                 if (sockfd >= FD_SETSIZE) {
 924                         logerror("Socket descriptor too large");
 925                         close(sockfd);
 926                         continue;
 927                 }
 928
 929 #ifdef IPV6_V6ONLY
 930                 if (ai->ai_family == AF_INET6) {
 931                         int on = 1;
 932                         setsockopt(sockfd, IPPROTO_IPV6, IPV6_V6ONLY,
 933                                    &on, sizeof(on));
 934                         /* Note: error is not fatal */
 935                 }
 936 #endif
 937
 938                 if (set_reuse_addr(sockfd)) {
 939                         logerror("Could not set SO_REUSEADDR: %s", strerror(errno));
 940                         close(sockfd);
 941                         continue;
 942                 }
 943
 944                 if (bind(sockfd, ai->ai_addr, ai->ai_addrlen) < 0) {
 945                         logerror("Could not bind to %s: %s",
 946                                  ip2str(ai->ai_family, ai->ai_addr, ai->ai_addrlen),
 947                                  strerror(errno));
 948                         close(sockfd);
 949                         continue;       /* not fatal */
 950                 }
 951                 if (listen(sockfd, 5) < 0) {
 952                         logerror("Could not listen to %s: %s",
 953                                  ip2str(ai->ai_family, ai->ai_addr, ai->ai_addrlen),
 954                                  strerror(errno));
 955                         close(sockfd);
 956                         continue;       /* not fatal */
 957                 }
 958
 959                 flags = fcntl(sockfd, F_GETFD, 0);
 960                 if (flags >= 0)
 961                         fcntl(sockfd, F_SETFD, flags | FD_CLOEXEC);
 962
 963                 ALLOC_GROW(socklist->list, socklist->nr + 1, socklist->alloc);
 964                 socklist->list[socklist->nr++] = sockfd;
 965                 socknum++;
 966         }
 967
 968         freeaddrinfo(ai0);
 969
 970         return socknum;
 971 }
 972
 973 #else /* NO_IPV6 */
 974
 975 static int setup_named_sock(char *listen_addr, int listen_port, struct socketlist *socklist)
 976 {
 977         struct sockaddr_in sin;
 978         int sockfd;
 979         long flags;
 980
 981         memset(&sin, 0, sizeof sin);
 982         sin.sin_family = AF_INET;
 983         sin.sin_port = htons(listen_port);
 984
 985         if (listen_addr) {
 986                 /* Well, host better be an IP address here. */
 987                 if (inet_pton(AF_INET, listen_addr, &sin.sin_addr.s_addr) <= 0)
 988                         return 0;
 989         } else {
 990                 sin.sin_addr.s_addr = htonl(INADDR_ANY);
 991         }
 992
 993         sockfd = socket(AF_INET, SOCK_STREAM, 0);
 994         if (sockfd < 0)
 995                 return 0;
 996
 997         if (set_reuse_addr(sockfd)) {
 998                 logerror("Could not set SO_REUSEADDR: %s", strerror(errno));
 999                 close(sockfd);
1000                 return 0;
1001         }
1002
1003         if ( bind(sockfd, (struct sockaddr *)&sin, sizeof sin) < 0 ) {
1004                 logerror("Could not bind to %s: %s",
1005                          ip2str(AF_INET, (struct sockaddr *)&sin, sizeof(sin)),
1006                          strerror(errno));
1007                 close(sockfd);
1008                 return 0;
1009         }
1010
1011         if (listen(sockfd, 5) < 0) {
1012                 logerror("Could not listen to %s: %s",
1013                          ip2str(AF_INET, (struct sockaddr *)&sin, sizeof(sin)),
1014                          strerror(errno));
1015                 close(sockfd);
1016                 return 0;
1017         }
1018
1019         flags = fcntl(sockfd, F_GETFD, 0);
1020         if (flags >= 0)
1021                 fcntl(sockfd, F_SETFD, flags | FD_CLOEXEC);
1022
1023         ALLOC_GROW(socklist->list, socklist->nr + 1, socklist->alloc);
1024         socklist->list[socklist->nr++] = sockfd;
1025         return 1;
1026 }
1027
1028 #endif
1029
1030 static void socksetup(struct string_list *listen_addr, int listen_port, struct socketlist *socklist)
1031 {
1032         if (!listen_addr->nr)
1033                 setup_named_sock(NULL, listen_port, socklist);
1034         else {
1035                 int i, socknum;
1036                 for (i = 0; i < listen_addr->nr; i++) {
1037                         socknum = setup_named_sock(listen_addr->items[i].string,
1038                                                    listen_port, socklist);
1039
1040                         if (socknum == 0)
1041                                 logerror("unable to allocate any listen sockets for host %s on port %u",
1042                                          listen_addr->items[i].string, listen_port);
1043                 }
1044         }
1045 }
1046
1047 static int service_loop(struct socketlist *socklist)
1048 {
1049         struct pollfd *pfd;
1050         int i;
1051
1052         pfd = xcalloc(socklist->nr, sizeof(struct pollfd));
1053
1054         for (i = 0; i < socklist->nr; i++) {
1055                 pfd[i].fd = socklist->list[i];
1056                 pfd[i].events = POLLIN;
1057         }
1058
1059         signal(SIGCHLD, child_handler);
1060
1061         for (;;) {
1062                 int i;
1063
1064                 check_dead_children();
1065
1066                 if (poll(pfd, socklist->nr, -1) < 0) {
1067                         if (errno != EINTR) {
1068                                 logerror("Poll failed, resuming: %s",
1069                                       strerror(errno));
1070                                 sleep(1);
1071                         }
1072                         continue;
1073                 }
1074
1075                 for (i = 0; i < socklist->nr; i++) {
1076                         if (pfd[i].revents & POLLIN) {
1077                                 union {
1078                                         struct sockaddr sa;
1079                                         struct sockaddr_in sai;
1080 #ifndef NO_IPV6
1081                                         struct sockaddr_in6 sai6;
1082 #endif
1083                                 } ss;
1084                                 socklen_t sslen = sizeof(ss);
1085                                 int incoming = accept(pfd[i].fd, &ss.sa, &sslen);
1086                                 if (incoming < 0) {
1087                                         switch (errno) {
1088                                         case EAGAIN:
1089                                         case EINTR:
1090                                         case ECONNABORTED:
1091                                                 continue;
1092                                         default:
1093                                                 die_errno("accept returned");
1094                                         }
1095                                 }
1096                                 handle(incoming, &ss.sa, sslen);
1097                         }
1098                 }
1099         }
1100 }
1101
1102 #ifdef NO_POSIX_GOODIES
1103
1104 struct credentials;
1105
1106 static void drop_privileges(struct credentials *cred)
1107 {
1108         /* nothing */
1109 }
1110
1111 static struct credentials *prepare_credentials(const char *user_name,
1112     const char *group_name)
1113 {
1114         die("--user not supported on this platform");
1115 }
1116
1117 #else
1118
1119 struct credentials {
1120         struct passwd *pass;
1121         gid_t gid;
1122 };
1123
1124 static void drop_privileges(struct credentials *cred)
1125 {
1126         if (cred && (initgroups(cred->pass->pw_name, cred->gid) ||
1127             setgid (cred->gid) || setuid(cred->pass->pw_uid)))
1128                 die("cannot drop privileges");
1129 }
1130
1131 static struct credentials *prepare_credentials(const char *user_name,
1132     const char *group_name)
1133 {
1134         static struct credentials c;
1135
1136         c.pass = getpwnam(user_name);
1137         if (!c.pass)
1138                 die("user not found - %s", user_name);
1139
1140         if (!group_name)
1141                 c.gid = c.pass->pw_gid;
1142         else {
1143                 struct group *group = getgrnam(group_name);
1144                 if (!group)
1145                         die("group not found - %s", group_name);
1146
1147                 c.gid = group->gr_gid;
1148         }
1149
1150         return &c;
1151 }
1152 #endif
1153
1154 static void store_pid(const char *path)
1155 {
1156         FILE *f = fopen(path, "w");
1157         if (!f)
1158                 die_errno("cannot open pid file '%s'", path);
1159         if (fprintf(f, "%"PRIuMAX"\n", (uintmax_t) getpid()) < 0 || fclose(f) != 0)
1160                 die_errno("failed to write pid file '%s'", path);
1161 }
1162
1163 static int serve(struct string_list *listen_addr, int listen_port,
1164     struct credentials *cred)
1165 {
1166         struct socketlist socklist = { NULL, 0, 0 };
1167
1168         socksetup(listen_addr, listen_port, &socklist);
1169         if (socklist.nr == 0)
1170                 die("unable to allocate any listen sockets on port %u",
1171                     listen_port);
1172
1173         drop_privileges(cred);
1174
1175         loginfo("Ready to rumble");
1176
1177         return service_loop(&socklist);
1178 }
1179
1180 int main(int argc, char **argv)
1181 {
1182         int listen_port = 0;
1183         struct string_list listen_addr = STRING_LIST_INIT_NODUP;
1184         int serve_mode = 0, inetd_mode = 0;
1185         const char *pid_file = NULL, *user_name = NULL, *group_name = NULL;
1186         int detach = 0;
1187         struct credentials *cred = NULL;
1188         int i;
1189
1190         git_setup_gettext();
1191
1192         git_extract_argv0_path(argv[0]);
1193
1194         for (i = 1; i < argc; i++) {
1195                 char *arg = argv[i];
1196                 const char *v;
1197
1198                 if (skip_prefix(arg, "--listen=", &v)) {
1199                         string_list_append(&listen_addr, xstrdup_tolower(v));
1200                         continue;
1201                 }
1202                 if (skip_prefix(arg, "--port=", &v)) {
1203                         char *end;
1204                         unsigned long n;
1205                         n = strtoul(v, &end, 0);
1206                         if (*v && !*end) {
1207                                 listen_port = n;
1208                                 continue;
1209                         }
1210                 }
1211                 if (!strcmp(arg, "--serve")) {
1212                         serve_mode = 1;
1213                         continue;
1214                 }
1215                 if (!strcmp(arg, "--inetd")) {
1216                         inetd_mode = 1;
1217                         log_syslog = 1;
1218                         continue;
1219                 }
1220                 if (!strcmp(arg, "--verbose")) {
1221                         verbose = 1;
1222                         continue;
1223                 }
1224                 if (!strcmp(arg, "--syslog")) {
1225                         log_syslog = 1;
1226                         continue;
1227                 }
1228                 if (!strcmp(arg, "--export-all")) {
1229                         export_all_trees = 1;
1230                         continue;
1231                 }
1232                 if (skip_prefix(arg, "--access-hook=", &v)) {
1233                         access_hook = v;
1234                         continue;
1235                 }
1236                 if (skip_prefix(arg, "--timeout=", &v)) {
1237                         timeout = atoi(v);
1238                         continue;
1239                 }
1240                 if (skip_prefix(arg, "--init-timeout=", &v)) {
1241                         init_timeout = atoi(v);
1242                         continue;
1243                 }
1244                 if (skip_prefix(arg, "--max-connections=", &v)) {
1245                         max_connections = atoi(v);
1246                         if (max_connections < 0)
1247                                 max_connections = 0;            /* unlimited */
1248                         continue;
1249                 }
1250                 if (!strcmp(arg, "--strict-paths")) {
1251                         strict_paths = 1;
1252                         continue;
1253                 }
1254                 if (skip_prefix(arg, "--base-path=", &v)) {
1255                         base_path = v;
1256                         continue;
1257                 }
1258                 if (!strcmp(arg, "--base-path-relaxed")) {
1259                         base_path_relaxed = 1;
1260                         continue;
1261                 }
1262                 if (skip_prefix(arg, "--interpolated-path=", &v)) {
1263                         interpolated_path = v;
1264                         continue;
1265                 }
1266                 if (!strcmp(arg, "--reuseaddr")) {
1267                         reuseaddr = 1;
1268                         continue;
1269                 }
1270                 if (!strcmp(arg, "--user-path")) {
1271                         user_path = "";
1272                         continue;
1273                 }
1274                 if (skip_prefix(arg, "--user-path=", &v)) {
1275                         user_path = v;
1276                         continue;
1277                 }
1278                 if (skip_prefix(arg, "--pid-file=", &v)) {
1279                         pid_file = v;
1280                         continue;
1281                 }
1282                 if (!strcmp(arg, "--detach")) {
1283                         detach = 1;
1284                         log_syslog = 1;
1285                         continue;
1286                 }
1287                 if (skip_prefix(arg, "--user=", &v)) {
1288                         user_name = v;
1289                         continue;
1290                 }
1291                 if (skip_prefix(arg, "--group=", &v)) {
1292                         group_name = v;
1293                         continue;
1294                 }
1295                 if (skip_prefix(arg, "--enable=", &v)) {
1296                         enable_service(v, 1);
1297                         continue;
1298                 }
1299                 if (skip_prefix(arg, "--disable=", &v)) {
1300                         enable_service(v, 0);
1301                         continue;
1302                 }
1303                 if (skip_prefix(arg, "--allow-override=", &v)) {
1304                         make_service_overridable(v, 1);
1305                         continue;
1306                 }
1307                 if (skip_prefix(arg, "--forbid-override=", &v)) {
1308                         make_service_overridable(v, 0);
1309                         continue;
1310                 }
1311                 if (!strcmp(arg, "--informative-errors")) {
1312                         informative_errors = 1;
1313                         continue;
1314                 }
1315                 if (!strcmp(arg, "--no-informative-errors")) {
1316                         informative_errors = 0;
1317                         continue;
1318                 }
1319                 if (!strcmp(arg, "--")) {
1320                         ok_paths = &argv[i+1];
1321                         break;
1322                 } else if (arg[0] != '-') {
1323                         ok_paths = &argv[i];
1324                         break;
1325                 }
1326
1327                 usage(daemon_usage);
1328         }
1329
1330         if (log_syslog) {
1331                 openlog("git-daemon", LOG_PID, LOG_DAEMON);
1332                 set_die_routine(daemon_die);
1333         } else
1334                 /* avoid splitting a message in the middle */
1335                 setvbuf(stderr, NULL, _IOFBF, 4096);
1336
1337         if (inetd_mode && (detach || group_name || user_name))
1338                 die("--detach, --user and --group are incompatible with --inetd");
1339
1340         if (inetd_mode && (listen_port || (listen_addr.nr > 0)))
1341                 die("--listen= and --port= are incompatible with --inetd");
1342         else if (listen_port == 0)
1343                 listen_port = DEFAULT_GIT_PORT;
1344
1345         if (group_name && !user_name)
1346                 die("--group supplied without --user");
1347
1348         if (user_name)
1349                 cred = prepare_credentials(user_name, group_name);
1350
1351         if (strict_paths && (!ok_paths || !*ok_paths))
1352                 die("option --strict-paths requires a whitelist");
1353
1354         if (base_path && !is_directory(base_path))
1355                 die("base-path '%s' does not exist or is not a directory",
1356                     base_path);
1357
1358         if (inetd_mode) {
1359                 if (!freopen("/dev/null", "w", stderr))
1360                         die_errno("failed to redirect stderr to /dev/null");
1361         }
1362
1363         if (inetd_mode || serve_mode)
1364                 return execute();
1365
1366         if (detach) {
1367                 if (daemonize())
1368                         die("--detach not supported on this platform");
1369         } else
1370                 sanitize_stdfds();
1371
1372         if (pid_file)
1373                 store_pid(pid_file);
1374
1375         /* prepare argv for serving-processes */
1376         cld_argv = xmalloc(sizeof (char *) * (argc + 2));
1377         cld_argv[0] = argv[0];  /* git-daemon */
1378         cld_argv[1] = "--serve";
1379         for (i = 1; i < argc; ++i)
1380                 cld_argv[i+1] = argv[i];
1381         cld_argv[argc+1] = NULL;
1382
1383         return serve(&listen_addr, listen_port, cred);
1384 }